Indoor Radon Concentration in Gorgan 212 Dwellings Using CR-39 Detector

Background and Radon is a colorless inert gas which decay products are the main component of natural radioactive elements that are naturally produced in under layers of earth crust by decay of radium and uranium. It enters through buildings via gaps and cracks. Alpha particle emissions as a radon gas decay product can increase the incidence of lung cancer in human. Every person spends 65 to 95 percent of his life in closed environments, therefore, elevated concentrations of radon could negatively influence human health. This study aimed at measuring the indoor radon concentration in the dwelling of Gorgan and compare it with EPA standards. The indoor radon concentration was measured in 212 homes in Gorgan using solid-state nuclear track detectors (CR-39). Each CR-39 detector was mounted 50-90 cm from the bottom bedroom and living rooms, away from doors and windows. After about three months of exposure, the detectors were collected and transported to the laboratory. In next step, they were etched in 6.25N NaOH solutions at 85 C˚ for three hours. Finally, track densities were analyzed using an optical microscope scanning system. The radon concentration in three percent of the houses was found higher than 148 Bq/m3 receipted by EPA as the action level. The result of this study could be used in mapping of national radon level.